2018 ASHS Annual Conference

Carrot is a very widely grown vegetable that is not only a valuable cash crop, but also an excellent source of Vitamin A derived from the orange pigments familiar to consumers. Carrot production has historically been in cooler climates, but with the development of carrot cultivars for subtropical regions of Brazil in the last 40 years, carrot production has expanded dramatically in warmer climates around the world. For example, carrot production in Bangladesh has risen significantly in recent years. Since most of the global incidence of Vitamin A deficiency is in warmer regions of the world, the development of carrot cultivars adapted to subtropical climates takes on even greater potential importance. Cultivated carrot germplasm is genetically and phenotypically diverse, and crossable wild relatives are a reservoir of even more genetic diversity. Wild carrot germplasm has been collected in very warm, dry, and, in some cases, very saline sites, and this germplasm is available in the USDA carrot germplasm collection. This project evaluated carrot wild relatives and cultivated carrots in warm, dry, saline field conditions, intercrossed climate-tolerance from wild relatives to adapted, nutritious cultivated germplasm, and evaluated intercrosses among carrots and their derivatives in hot, dry, saline field sites in Bangladesh and Pakistan. Exposure to heat and salinity in field trials was effective in limiting growth for most of the germplasm entries evaluated, whereas exposure to drought did not limit carrot growth as dramatically as heat or salt. Of particular interest, a few entries demonstrated heat, drought, and salinity tolerance in both Bangladesh and Pakistan. Intercrosses involving plants with novel abiotic stress resilience traits of carrot crop wild relatives (CWRs) with highly nutritious, good flavor, widely-grown carrot types were initiated in both Bangladesh and Pakistan, and seed production was successful in subsequent generations. Tolerance for heat, salinity, and drought was discovered among carrot germplasm accessions evaluated and, for selected entries, was reliably demonstrated across both locations and across several years. Interestingly, among tolerant germplasm accessions, many were cultivated carrot. While wild carrot relatives also demonstrated repeatable tolerance, the incidence of tolerant cultivated carrots suggests that genes in cultivated background can be tapped to develop breeding populations with good horticultural quality favorable to both farmers and consumers. The inheritance of tolerance is being evaluated and germplasm is being developed.